LAUSR

Abstract The corrosion inhibition efficiency of tetradecyltrimethylammonium bromide (TTAB) in presence of Sunset Yellow (SY) was investigated in NaCl corrosive medium using Tafel linear polarization method, electrochemical impedance spectroscopy (EIS), gravimetric measurement, and Density functional theory (DFT) calculations. Scanning electron microscopy (SEM), Fourier transform infrared (FTIR) and UV–visible spectroscopy techniques were also employed to study the morphology of corrected surface and the nature of adsorbed layer. It was revealed that TTAB micelles exhibit low corrosion inhibition efficiency at high concentration for mild steel in NaCl, while the inhibition efficiency was drastically increased in TTAB-SY mixed system, reaching higher than 90% in the presence of 100 uM TTAB- SY(1:1). Different corrosion mechanisms were proposed in the presence and absence of dye. A noticeable Warburg resistance was observed in the absence of dye while no Warburg was seen in the presence of dye indicating that the mechanism is mainly changed. Also, the results indicated that TTAB-SY ion pairs act as mixed-type inhibitors. Finally, from the optimized geometry of TTAB, SY, and TTAB-SY complexes and also electron distribution in HOMO and LUMO, possible modes of interaction of TTAB-SY complexes with mild steel surface have been predicted.